Unipolar exciter for turbo-generators.



H. HERTZ. UNIPOLAR EXCITER FOR TURBO-GENERATORS.

APPLICATION FILED JUNE3,1907.

Patented Apr. 4; 1911.

such as a unipolar generator.

UNITED STATES PATENT OFFICE.

HJALMAR nna'rz, OF cmcaeo, rumors, ASSIGNOR, BY IMEISNE ASSIGNMENTS, "r0

GENERAL ELECTRIC COMPANY, A CORPORATION on NEW YORK.

UNIPOLAR EXCITER FOR TURBO-GENERATORS.

Chicago, in the county of Cook and Stateof i Illinois, have invented acertain new and useful Improvement in Unipolar Exciters forTurbo-Generators, of which the follow-.

ing" is a full, clear, concise, and exact description.

My inventlon relates to dynamo electric machines, more particularly tothe class in which-the revolving field or rotor thereof is excited bycurrent from an external In the operation of turbine driven alternatorsof the revolving field type running at comparatively high speed, it isdesirable for various reasons to excite the field thereof by directcurrent of comparatively low voltage,

and for generating this current, -ithas been found practicable to employa 'unip'olar generator as an exciter for the revolving field.

Heretofore the armature of the exciter has usually been connecteddirectly'to the shaft of the revolving field or rotor. The terminals ofthe revolving field Winding have been brought out to two collector.rings on the shaft, and the'current for exciting this field has beenled from the terminals of the umpolar exciter to brushes contacting withsaid collector rings, thus making itneoessary to have four sets ofbrushes; two sets on the unipolar exciter, and twofor the collectorrings. The resistance of the brushes and [the variable contact madewiththe collector rings due to the high speed causes anapprecomparatively quite low.

1 The principal object of'my invention is toreduce this resistance andconsequently the loss in voltage to a minimum, and to this end I mountthearmature of a unipolar generator directly upon the end clamping plateof the revolving field'so that the current generated in said armatureW11]. flow directly into the field winding instead of through interveninrings as has hereto ore been the case. The armature may be castintegrally with the end clamping plate, or it may be attached thereto byany suitable means. 3 1

A further object of my invention is to de crease the total length of theWhole machine more than has heretofore been possible since source,"

Y 3 1s a view 1n section of a portion of an end brushes and collectorspecificationof, Ietters'iatent. Patented Apr; 4,1911. Application filedJune" a,

190?. Serial No. 376,906.

., the-rotor and exciter form a very compact and unitary structure,thusmaking it .possible to use a shortershaft. g

I will describe my invention by referen e, to the accompanying drawings,wherein a f Figure 1 is a view of a revolving field with a unipolarexciter mounted at oneend there.

of said fieldbeingshown insection. Fig.2

is a view of'a revolving field with a unipolar exclter mounted'at eachend thereof, the unipolar exoiter being shown in section] Fig.

plate showing the armature of the exciter bolted to said end plate ofthe revolving of, the unipolar machine'and the end plate field. Fig.i'is a diagrammatic view, the

unipolar exciters being shown in section.

Similar reference characters are used to designate similar partsthroughout the severalviews. v I I p s The revolving field or rotor Aofan alternating current generatoris mounted ona shaft S, andconstructed with clamping are connected 'to andform the terminalsof therevolving field winding A. Thenend plates a b at the ends thereof.Theseplatesplate I) has formed thereon a collector ring #6 upon which abrush d is adapted to bear. C is a 'unipolar generator of well knownconstruction having a cylindrical armature tegrally with the clampingplated; of the in any'suitable i'nanner, for instance,":tli'e The endplate B, instead of carrying a 001-.

lector ring as in 'Fig. 1 is formed with a unipolar armature g and thebrush (Z will contact with-the outer edge of said armature zinsteadofwith collector ring I), as in F ig.

will explain the advantages of this arrevolving field, but it may befastened thereto a This armature is preferablyfOrmedinarmature may bebolted'to the end clamping 5 plate'as shown in Fig. 3. A brush 6 isadapted'tobear on the outer edge lot the: cyli1i-'- high speed at whichit is run to, properly collect the current therefrom. By'using a smallerexciter at each end" of the rotor instead of one large exeiter at oneend thereof, I obtain the same total sectional area with smallerdiameter of the armature. Consequently the current. may be more easilycollected therefrom, while at the same time it will be better able towithstand the strains imposed upon it due to the centrifugal forceattendant upon the high speed.

of rotation. F u'rthermore,.the heat radiating surfaces and consequentlythe heat dissipation will be-considerably greater in the two excitersthan in the one.

Referring to Fig. 1, during the operation of the machine the fieldmagnets of the unipolar excite'r' inducecurrent in the'arm ature a. Thiscurrent will pass directly into the revolving field winding through theend plate a, collector ring 5, brush (1, circuit f, brush 0, back to theunipolar armature. Thus it will be seen that a minimum number ofcollector'rings and brushes are used. The same operation takes place inthe structure shown in-Fig. 2, except that a current is also. generatedin the armature g of the exeiter D, which assists the current from thearmature on since the two armatures may be placed in series.

In Fig. 4 I have shown diagrammatically a field winding for a rotor,with which my invention is particularly, though not necessarily, adaptedto be used. This field winding and the manner in which it is associatedwith the rotor, however, forms no part of my present invention, but isfully deserlbed in my Patent No. 908,098 dated December 29, 1908.

Having described my invention, I claim:

1. In a dynamo-electric machine, the combination with a rotor providedwith a field winding, of a'unipolar exciter therefor pro- 4. Incombination in a dynamo-electric machine, a revolving field-and awinding therefor,-and end clamping plates comprising the terminals ofsaid field, of a unipolar dynamo for energizing said field windinghaving a cylindrical armature carried by one of said plates, and acircuit uniting said cylindrical armature and the other end plate;whereby current generated in said armature flows" directly therefromthrough the field winding.

5. In a dynamo-electric machine, the combination with arevolving fieldand an exciting winding therefor, clamping plates at each end thereofforming the terminals of said winding, a cylinder carried by each 'plateadapted to serve as the armature of a unipolar exciter, a field magnetada ted to induce current in said cylinder, rushes bearing on saidarmature and a circuit uniting said brushes whereby current generated insaid armatures flows directly therefrom to the field winding.

' 6. .In a, dynamo-electric machine, the combination with a rotorprovided with a field winding and end plates constitutin terminals ofsaid winding, of cylindrica extensions projecting from said plates,brushes engaging said cylindrical extensions, a circuit connecting saidbrushes, and exciting fields for said cylindrical extensions, saidextensions and fields constituting unipolar exciters for the rotor fieldwinding,

' In witness weherof, I,'hereunto subscribe my name this 28th day of MayA. D., 1907 HJALMAR HERTZ.

lVitnesses i HARRY BIERMA, E. F. BEAUBIEN.

